There is a continuous drive in the electronics industry to miniaturize integrated circuits, for a variety of reasons well known to those skilled in the art. Significant developments in the semiconductor industry were made possible by advances in photolithography, from the micron scale to the nanometer scale, but the physical resolution limits of optical lithography have now almost been reached, thus constraining further advancement. However, continued growth of the semiconductor industry depends on increasing the performance and reducing the cost of integrated circuits on a silicon substrate.
Recent developments in extreme ultraviolet (EUV) lithography, at 13.5 nm, has enabled some further scaling/miniaturization of integrated circuits, but enormous challenges still obstruct the full implementation of this technique in the semiconductor industry.
Electron-beam lithography (e-beam, EBL) has been considered as a potential complement to optical lithography on account of its high resolution. However, EBL is a notoriously slow process because it essentially involves slowly writing with an electron beam rather than simply exposing a photoresist to diffuse radiation through a photomask, as with of photolithography. To produce the dimensions required of an integrated circuit, an e-beam must be directed and held at a specific place on a resist material for a specific amount of time (“dwell time”, usually nanoseconds) before being gradually moved across the resist in a desired pattern. The “step size”, which determines the resolution (i.e. the size of each incremental step the e-beam makes during EBL), is typically of the order of about 10 nm, meaning that the overall EBL process is extremely protracted for a typical wafer 45 cm in size.
It is therefore an object of the present invention to solve at least one of the problems of the prior art.
Another object of the invention is to increase electron beam lithography write-speeds.
Another object of the invention is to decrease the intensity of incident exposure radiation required by lithography (whether e-beam or another form of radiation).
Another object of the invention is to reduce the amount of materials used in lithography, such as resist-coating materials.
Another object is to increase aspect ratios in lithography.
Another object is to increase resolution in lithography.